Effects and Impacts: Canterbury

Major Impacts

Understanding Climate Change for Land Managers

• There is a forecast of substantial advantages arising from the increased potential to grow a more diverse range of crops in low-lying areas.

However, there are concerns about potential challenges related to the predicted increase in water requirements and the exacerbation of both the frequency and severity of droughts.

It is projected that the average annual temperatures in Canterbury will rise by approximately 1.0°C by mid-century, and by 2.0°C or more by the end of the century. The most significant temperature increases are expected to be experienced during the winter season.

Furthermore, there is a likelihood of an increase in annual rainfall in inland Canterbury and the Southern Alps, while coastal Canterbury from Banks Peninsula north may experience lower rainfall levels than at present. Winters in the Canterbury Plains may become drier than the current norm, while inland areas and the Alps could experience increased precipitation.

Potential Impacts and Opportunities

The forecast for drier average conditions and heightened drought susceptibility in the Canterbury plains is expected to lead to an increased demand for water resources. The foremost concern for Canterbury in the foreseeable future is anticipated to be the security of its water supply, even in the absence of the most severe consequences of climate change. The combination of drier conditions during summer months and escalating water requirements is likely to strain available resources. Addressing this challenge will necessitate meticulous planning and the adoption of progressively more efficient irrigation techniques and infrastructure.

Altered precipitation patterns, possibly resulting in increased rainfall in elevated areas and drier conditions on the plains, will have implications for various local and regional infrastructure components, including flood protection systems, community water schemes, culverts, bridges, erosion control measures, farm dams, water distribution networks, and irrigation facilities.

The warming trend in Canterbury is expected to create new prospects for arable farming and the cultivation of processing vegetables, making crops like sweetcorn and maize increasingly viable. The realization of enhanced crop production potential will hinge on future developments in irrigation capacity and the ability of surface and groundwater reservoirs to accommodate heightened demand, particularly from dairy farming expansions.

The productivity of temperate grains such as wheat could see an uptick, contingent upon increased fertilizer application and water availability. Changes in pest and disease patterns may occur across all arable and fruit crops, especially with milder winters.

Productivity in pastoral farming is projected to rise as long as water resources remain sufficient. Dryland farming in Canterbury is likely to face challenges such as prolonged periods of pasture deficit, shifts in species composition within dryland farming systems, and impacts on water reserves in drier conditions.

While there is currently no conclusive evidence of sub-tropical grass species posing a threat, the risk of invasive species establishing themselves over time is expected to grow, particularly on arid northern slopes in North Canterbury.

Projections indicate a potential 15 percent increase in annual rainfall in the Alps of South Canterbury, contrasting with a projected 6–8 percent decrease in coastal North Canterbury. By 2050, the Southern Alps could experience a rise of over 6 percent in annual rainfall, while lowland mid and North Canterbury may see a slight decrease in precipitation. The region faces an elevated biosecurity risk due to rising temperatures over time. This risk is exemplified by the potential proliferation of pests such as banana passionfruit, a frost-sensitive plant displaying signs of expansion, and argentine ants, which have demonstrated survival through two winters, defying previous expectations. Additionally, the likelihood of fires in rural coastal areas escalating poses significant concerns.